Occupant restraint systems for use in vehicles are well known in the art. One such restraint system includes a crash sensor, an inflatable air bag, and an actuation circuit that controls deployment of an air bag in response to an output signal from the crash sensor. The crash sensor may be an accelerometer that provides an electrical output signal having a value functionally related to the vehicle's deceleration. A controller evaluates the electrical output signal and provides an actuation signal when it determines a crash condition is occurring of such nature that the air bag should be deployed. An actuation circuit includes a squib operatively connected to a source of inflation fluid.
In response to an actuation signal from the controller, the actuation circuit applies a current through the squib which causes the squib to ignite. When the squib ignites, the source of inflation fluid discharges gas into the air bag. This results in inflation of the air bag.
The art has recognized that it is not always desirable to inflate the air bag with 100% of the gas provided from the source of inflation fluid. One proposed system, disclosed in U.S. Pat. No. 5,232,243 to Blackburn et al. and assigned to the assignee of the present invention, controls the amount of gas that inflates the air bag in response to the detected weight of the occupant. Another system, disclosed in U.S. Pat. No. 5,330,226 to Gentry et al. and assigned to the assignee of the present invention, controls the amount of gas that inflates the air bag in response to detected occupant position.
U.S. Pat. No. 5,074,583 to Fujita et al. proposes a system employing several sensors for determining occupant presence, location, and size (including height and weight) for controlling an air bag system.
None of the systems noted above determine occupant size or position based on employing an image sensor for viewing a field including a passenger seat with an occupant thereon and providing a block of image data representative thereof for comparison with a prestored block of image data representative of the same field with an unoccupied passenger seat. Such a comparison is employed in accordance with the present invention for controlling an occupant restraint system.